Tensile properties, hardness and phase formation of the nickel aluminides based composites doped with reduced graphene oxide (Al-Ni-rGO)

Nickel aluminides, namely NiAl, Ni3Al and NiAl3, based functional materials have the attractive properties for structural applications at elevated temperatures. However, the intermetallics in the Al-Ni system are rather brittle which limits their practical applications. Graphene and its derivatives are known to be excellent reinforcements for various metallic and ceramic matrices. In the present work 0.5 wt% reduced graphene oxide (rGO) was incorporated in the Al-Ni system for the first time using modified powder metallurgy technique. Phase composition, structures of powders and composite intermetallic materials were investigated via SEM, EDS, XRD, Raman spectroscopy and hydrostatic weighing. The effect of rGO on the phase formation, microstructure and mechanical properties of the composites was discussed. Via XRD it was shown, that rGO favors the formation of AlNi, Ni3Al and Al3Ni compounds in the Al-Ni system. The Al3Ni2 was shown to be first intermediate phase appearing in the phase sequence. Due to the reinforcement effect of rGO, 80nNi-rGO composite showed about 5 times higher tensile strength, about 3 times higher Young's modulus and improved elongation as compared to the same composition without rGO. The 40nNi-rGO and 51nNi-rGO composites exhibited superior hardness of 297 ± 28 HV0.3, 561 ± 121 HV0.3 and 640 ± 118 HV0.3.